The present invention is a method of altering an aspect of an electromagnetic energy wave in response to an acceleration force and more particularly to the altering of an electromagnetic energy wave, propagating in an optical switch that is responsive to an acceleration force.
Various types of acceleration responsive switches have been described in the prior art. For instance, U.S. Pat. No. 5,828,138 by McIver et al. discloses an acceleration switch wherein an inertial mass member is held in a holding position by an electrostatic force until the acceleration forces exerted upon it causes the inertial mass member to deflect to an actuated position. U.S. Pat. No. 5,600,109 by Mizutani et al. discloses an acceleration switch wherein acceleration forces cause an inertia ball to bridge one or more contacts located radially around the ball.
The present invention is a method and optical switch for altering an electromagnetic energy wave in response to an acceleration force.
The method of altering an electromagnetic energy wave in response to an acceleration force of the present invention comprises the step of disposing a material in the propagation path of the energy wave. This material changes optical properties in response to acceleration forces, such as vibration, shaking, or acceleration. The optical properties of the material change, so that the energy wave is altered.
The optical switch of the present invention comprises an electromagnetic energy source, an electromagnetic energy sensor, and a material, as described above, that changes optical properties in response to an acceleration force. The electromagnetic energy sensor is used to detect an electromagnetic energy wave that is generated by the electromagnetic energy source. The acceleration force responsive material is disposed in the propagation path of the electromagnetic energy wave, between the source and the sensor, so that when the material changes optical properties in response to an acceleration force, the electromagnetic energy wave is altered, causing the optical switch to change between an off and on condition.
The material mentioned previously is commonly referred to as xe2x80x9cthixotropicxe2x80x9d material. Thixotropic materials generally are materials that change from a solid state to a fluid state when exposed to acceleration forces. Typically, they are colloidal gels, which liquefy when agitated by shaking or by ultrasonic vibration and return to the gel state when at rest. Thixotropic materials further have the characteristic of changing optical properties when they change states. Some changing optical properties include an opaque material becoming transparent or a transparent material changing its index of refraction, both occurring when the material is subjected to an acceleration force. A number of thixotropic materials and additives to create thixotropic material are commercially available. King Industries markets a thixotropic material sold under the trademark Disparlon. Similarly, PPG Industries, Inc. offers synthetic precipitated silica thixotropic material sold under the trademark Hi-Sil T-600 and Hi-Sil T-700. Dow Corning sells and additive for silicone to make it thixotropic, Thixo A-300-1. RBC Industries makes available electrically conductive thixotropic materials, RBC-6200 and RBC-6400. Further information on thixotropic materials is provided in U.S. Pat. No. 5,503,777 by Itagaki et al., U.S. Pat. No. 5,334,630 by Francis et al., and U.S. Pat. No. 4,544,408 by Mosser et al.